A tiny chemical "brain" which could one day act as a remote control for swarms of nano-machines has been invented.

The molecular device - just two billionths of a metre across - was able to control eight of the microscopic machines simultaneously in a test.

Writing in Proceedings of the National Academy of Sciences, scientists say it could also be used to boost the processing power of future computers.

Many experts have high hopes for nano-machines in treating disease.

"If [in the future] you want to remotely operate on a tumour you might want to send some molecular machines there," explained Dr Anirban Bandyopadhyay of the International Center for Young Scientists, Tsukuba, Japan.

"But you cannot just put them into the blood and [expect them] to go to the right place."

Dr Bandyopadhyay believes his device may offer a solution. One day they may be able to guide the nanobots through the body and control their functions, he said.

"That kind of device simply did not exist; this is the first time we have created a nano-brain," he told BBC News.

Computer brain

The machine is made from 17 molecules of the chemical duroquinone. Each one is known as a "logic device".